Nasal mucosal metabolism of an LH-RH fragment and inhibition with boroleucine

Abstract

This study is a continuation of investigations of the metabolism of peptides by the rat nasal mucosa, and methods to inhibit metabolism. LH-RH 3–10 was rapidly metabolized by aminopeptidases when perfused through the isolated rat nasal cavity. Metabolism was almost completely inhibited by co-perfusing a very low concentration of boroleucine, an aminopeptidase inhibitor. LH-RH 3–10 is different from peptides previously evaluated in similar studies, in that non-polar amino acids are adjacent to the site of peptidase cleavage. This study shows that such peptides are metabolized by nasal aminopeptidases, and that metabolism can be inhibited by boroleucine.